When wellbores are prepared for oil and gas production, it is common to cement a casing string within the wellbore. Often, it may be desirable to cement the casing within the wellbore in multiple, separate stages.
Conventionally, cementing a casing string within a wellbore is achieved by flowing cement to the bottom of the casing string and upward into the annular space between the casing string and the wellbore walls. In order to preserve the integrity of the cementitious slurry used to cement the casing within the wellbore, “cementing plugs” or “wiper plugs” are used to form a barrier between the cementitious slurry and other servicing fluids and reduce intermixing or intermingling between the cementitious slurry and any other fluid. It may be desirable to employ subsurface release cementing plugs, that is, cementing plugs that are released from a point within the wellbore below the Earth's surface, in a cementing operation. However, conventional subsurface release plugs are limited in application, for example, because of the relatively large diameter of conventional subsurface release cementing plug systems.
Therefore, there is a need for improved subsurface release plugs that may be employed in a wider range of applications.